Children's positive transitions across systems in the early years is a concern nationally and locally, as states, early education programs, and public schools seek to have better collaboration, coordination and alignment across the systems that serve our youngest children. Yet, there is very little research available on coordination practices and the transition to school to inform policy and practice. This project seeks to fill a void in the current literature base in order to provide recommendations for policy and practices to improve Head Start and other programs serving young children. In close partnership with Communities United Head Start in Massachusetts, this proposal seeks funding for research to study the vertical coordination efforts between Head Start programs and elementary schools to enhance successful kindergarten transitions for low-income children. This topic directly addresses priority areas of the grant call, including the transition from Head Start to Kindergarten and community engagement and collaboration (ACF, 2016). The objectives of the study are to: 1) describe the coordination efforts that are used by Head Start programs to smooth children's transition to kindergarten, 2) examine the association between coordination practices and children's social and academic outcomes in kindergarten, 3) test whether there is an additive or interactive relationship between Head Start coordination efforts and elementary school-based transition practices, 4) test whether the relationship between coordination efforts and children's outcomes are moderated by child and family characteristics, and 5) gain a deeper understanding of the opportunities and barriers to coordinating across systems to support the transition to kindergarten. This study will provide a nuanced view of the coordination between preschool settings and elementary schools, going beyond prior research which solely examined sharing of information across systems. With the goal of extending implications for policy and practice to the diverse early education system and elementary schools, this project employs a two-phase explanatory sequential design, beginning with a quantitative phase, followed by a qualitative phase. Phase I of the study addresses the first four study objectives through a secondary data analysis of the Head Start FACES 2009 data, assessing vertical coordination practices reported by Head Start center directors and their relationship to child outcomes in kindergarten, as well as factors that moderate the relationship. To contextualize the findings from phase I in the lived experiences of practitioners, phase II will employ a qualitative study technique to collect and analyze interview and focus group data from Head Start directors and teachers, and elementary school principals and teachers (addressing objective 4). Through close collaboration with the Head Start partner and an advisory committee of key early education policymakers and practitioners, this study seeks to delineate the direct needs of the field, and inform the next generation of policy and practice initiatives.